Significance of magnetic field and stratification effects on the bioconvective stagnation-point flow of ferro-nanofluid over a rotating stretchable disk: Four-factor response surface methodology

Owing to its practical application in pharmaceuticals, biosensors, medical instruments, bio-chromatography, microchip pump, biomedical science, micro-actuators, and aerodynamics, the bioconvective stagnation-point flow over a whirling extendible disk is investigated. The nanomaterial flow has been modeled using the modified Buongiorno nanofluid model. The impact of the stratification constraints and magnetic field are also accounted. Von Karman's similarity transformations are employed and the transmuted nonlinear ODEs are resolved using the finite-difference based bvp5c routine. MATLAB generated flow profiles have been analyzed for augmentations in the influential parameter values. It is found that the nanofluid temperature elevates with an augmentation in the volume fraction of magnetite nanoparticles and depletes with an augmentation in the thermal stratification parameter. The highest mass transfer rate is experienced for smaller values of solutal stratification parameter. The influence of magnetic field parameter (0.2 <= M <= 1.8), thermal stratification parameter (0.1 <= S1 <= 0.5), volume fraction of magnetite nanoparticles (0.01 <= phi <= 0.09), and velocity ratio parameter (0.1 <= S <= 0.5) on the heat transfer rate has been scrutinized statistically using a five-level four-factor response surface optimized model. A maximum error of 0.08% and the estimated coefficient of determination (99.99%) adjudge the correctness of the model. The heat transfer rate is observed to be negatively correlated with the thermal stratification parameter and the magnetic field parameter.